There is a continuing demand for electronic systems to perform more functions or operations in shorter periods of time. This typically requires additional components to perform the additional functions and to store more programs and data. At the same time packaging requirements are decreasing in size. Consumers want smaller, lighter weight products that do more and are more mobile or portable. Accordingly, circuit designers are challenged to provide more components and greater capacity per unit of area on a semiconductor die.
Most electronic circuits include basic electrical components such as transistors, resistors, inductors, capacitors and the like. Capacitors are one component that can occupy considerable area on a semiconductor die depending upon the size of the capacitor or the number of capacitors. For example, a memory system or device can include a large number of capacitors for storing information. Capacitors are typically made by depositing a first metal plate, depositing a layer of dielectric material over the first metal plate and then depositing a second metal plate over the layer of dielectric material and substantially parallel to the first metal plate. The size of the capacitance will be a function of the surface area of the two facing parallel plates and other parameters such as the dielectric constant of the dielectric material and the spacing between the plates. Accordingly, one primary means of increasing the capacitance, is to increase the size of each of the parallel plates but this will also consume more area on the semiconductor die.
As previously mentioned, some electronic circuits, such as memory devices or systems use capacitors to store data electronically. For example, a capacitor with a charge on it can represent a logic 1 and an uncharged capacitor can represent a logic 0. Accordingly, as electronic systems or computer systems are required to perform more functions and to store more programs and data, memory devices and systems will require more memory cells with each cell including a capacitor to store the information. Memory device and system designers are therefore challenged to provide more storage capacity while using a minimum amount of area on a semiconductor die. For efficiency and speed of operation, the stored information is also preferably located close to those components that access and use the information. Accordingly, memory devices or systems are often formed on the same chip or semiconductor die with other components and it becomes important in the manufacturing process that the operations to make the different components are compatible and do not adversely effect one another and that the different components can be manufactured efficiently with the lowest possible cost and time.
Accordingly, for the reason stated above, and for other reasons that will become apparent upon reading and understanding the present specification, there is a need for a capacitor or an array of capacitors that maximizes the amount of capacitance and number of capacitors per unit of area of a semiconductor die or chip. There is also a need for a capacitor or capacitor array that can be manufactured efficiently with minimal process operations and with process operations that are compatible with or do not interfere with other circuitry or components formed on the same semiconductor die.